Renal dysfunction or failure and end-stage renal disease causes the body to lose the ability to remove water and minerals, to excrete harmful metabolites, to maintain acid-base balance, and to control electrolyte and mineral concentrations within physiological ranges. Toxic uremic waste metabolites, including urea, creatinine, and uric acid, accumulate in the body's tissues which can result in a person's death if the filtration function of the kidney is not replaced.
Dialysis is commonly used to replace kidney function by removing these waste toxins and excess water. In one type of dialysis treatment—hemodialysis—toxins are filtered from a patient's blood externally in a hemodialysis machine. Blood passes from the patient through a dialyzer separated by a semi-permeable membrane from a large volume of externally-supplied dialysis solution. The waste and toxins dialyze out of the blood through the semi-permeable membrane into the dialysis solution, which is then discarded.
The dialysis solutions or dialysates used during hemodialysis typically contain sodium chloride and other electrolytes (e.g., calcium chloride, or potassium chloride), a buffer substance (e.g., bicarbonate, or acetate and acid) to establish a physiological pH. Other substances can also be included in certain dialysates.